Thanks to Brilliant for sponsoring today’s video.
On Earth, there are many tool-using creatures. From birds using tiny cactus needles to help
them to spear grubs, to sea otters using stones to crack open clams, it is through the use of tools
that they accomplish their goals of survival. Humans take this to a whole other level. Our tool
use has developed into advanced technology, that’s not just about survival but about curiosity,
which allows us to cross the expanse of space and land robotic rovers on other planets. But however
advanced our technology becomes, we press against limitations. Technology is a fantastic enabler,
but for every tool, there is an expiration date, and things it simply cannot do. However much our
tools can do, will they be enough to crack one of the universe’s most important mysteries?
I’m Alex McColgan, and you’re watching Astrum. And this is the question being
asked through the Perseverance Rover on Mars. Its mission is to collect samples from Mars’
surface that may contain proof of alien life. To discover that life can arise on planets other
than our own would radically change our whole understanding of ourselves and the universe...
But it is in a race against time. In the 5th video in this series, we will take a
closer look at some of that technology, and will see it in action from January 2022 till April,
during the next phase of Perseverance’s mission – its journey to the Delta in Jezero crater.
When we last saw the Perseverance rover, it had just emerged from the shifting sands to the south
of Séítah, a place filled with traps that could have spelt the end of Perseverance’s mission.
However, now that it was free from that dangerous terrain, it had a new target – the section of the
Jezero crater which contained its Delta. Since coming to Mars, Perseverance had taken many
samples from what was now understood to be two distinct geological formations – Máaz, and Séítah.
These two large bodies of rock were discovered to come from different time periods,
and were extremely useful in providing context to the geological history of Jezero crater.
This knowledge was in itself a tool. By understanding what Jezero’s history was,
scientists could pinpoint the most likely locations within the crater to
find ancient remains of life. And that crucial location was the Jezero Delta.
Scientists had long suspected the Delta was a likely source of fossilised evidence. Billions of
years ago, a large watershed many times the size of Jezero crater itself drained into the crater.
As the water travelled, it picked up pieces of rock from a massive catchment area, before
depositing it all into the crater. Over time, silt and sand would have buried these rocks, hopefully
preserving their secrets in protective clay – one of the most radiation-resistant forms of rock,
ideal for preserving biological markers and complex organic molecules. If life ever existed
in the waters of Jezero, it was most likely that the proof of it lay in the Delta. Which was why it
was time for Perseverance to really start booking it. The sands of Séítah had forced Perseverance to
travel with care, picking its route carefully to avoid getting trapped in any loose sand. However,
the terrain outside of Séítah is much smoother. This allowed Perseverance to unleash its full
potential. As it travelled up and around the outside of the dunes of Séítah, Perseverance
proved itself by setting the land speed record for a Rover on Mars: 319.8m travelled in a single day.
Admittedly, that does not sound very fast - this distance is only about the length of 3
football pitches – but this is impressive for a Mars rover. This was roughly 50% further in
one day than the previous record of 220 m set by the Opportunity rover in 2005. And bear in mind,
it did all of this by itself, choosing its route with its autonomous AI system, Autonav.
Being able to assess the terrain around it, on the fly and by itself, the fact it could pick out the
best route to avoid obstacles and rough patches is incredible. And given that Perseverance’s
top speed is believed to be 120 m per hour, Perseverance still has a lot of reserves to
tap into. And Perseverance was not done there. It also completed the first multi-day drive on Mars,
managing to keep driving without any input from Earth over a 3-day period. This has always proved
challenging for Rovers. Usually human intervention is required and regular updates are needed to help
negate the uncertainty that always creeps into a Rover’s awareness of where it is.
Without this intervention, it may get lost, possibly heading into dangerous areas.
But Perseverance’s Autonav is able to circumvent this issue. Although some uncertainty does still
creep in, Perseverance is able to keep track of its own location well enough that it can be left
to run without these regular updates, potentially meaning it can be left to run over weekends
or holidays without any supervision from Earth. This allows it to travel much faster and further,
getting to the places where the best science can happen. Not that Perseverance wasn’t doing
science along the way to the Delta. It just did some of it autonomously, too. Oh, and I think
it’s time we talked about Perseverance’s heat ray, which it can use – you guessed it – autonomously.
Yes, Perseverance has a heat ray, which it can decide for itself when to deploy.
When I first heard about this, I began to suspect that whoever designed Perseverance had read War of
the Worlds, and wanted to circumvent any possible invasion of Earth by getting the first hit in. And
while this isn’t likely the case, Perseverance’s laser - known as SuperCam - is no joke. It can
heat rocks to a temperature of 10,000°C, melting them to plasma and vaporising them.
Before you ask, this incredible tool is designed for use in evaluating the chemical composition
of rocks, not for vaporising aliens. By heating rocks up to such a temperature,
the light that they start to emit can be evaluated to see which chemical markers it carries.
Different elements and compounds release light at different wavelengths. By seeing what light a rock
emits or doesn’t emit when super-heated can be key in identifying its chemical composition, for some
on-site scientific analysis. Also, it should be noted that this is done on a very very tiny scale.
On the 11th of March 2022, Perseverance zapped one fascinatingly purple-coloured rock a total
of 150 times in the same spot, vaporising its outer layers to see what lay behind the surface.
However, all these repeated vaporisations only bored a hole into the rock that was
a single millimetre deep. Hardly a weapon for fighting Martians.
But these are the tools Perseverance employs as it continues its journey, working with
scientists along the way to abrade and laser various samples, for a little en-route science.
It even accidentally picked up a pet rock along the way in one of its wheels. This small stone was
deemed to not hinder the rover’s movements in any way, so scientists have left it be. So far, the
rock has accompanied Perseverance over a distance of 8.5km, over the course of 4 months, and has
proved to be far less of a danger to its mission than the last rocks that it accidentally acquired.
But with the arrival of one friend, another would begin to depart. Technology, although impressive,
is not infallible. On the 3rd of May, 2022, as Perseverance was reaching the end of its journey
towards Jezero’s Delta, communications dropped out with Ingenuity. The Ingenuity helicopter had
accompanied Perseverance since the beginning of its journey, the two machines travelling
together to the red planet and helping each other perform their different missions. Ingenuity had
already amazed the world by being the first flying machine on Mars. It had scouted out the route for
Perseverance during most of its mission, spotting hazards in advance so Perseverance could avoid
them. But Ingenuity’s intended lifespan of 30 days was already long past. Every day the helicopter
still functioned was a gift, and one that could not keep giving forever. When Ingenuity first
started off on its routine flight, Perseverance thought nothing of it. The two machines weren’t
always in line-of-sight with each other, instead keeping contact with frequent radio check-ins.
However, when the next scheduled call should have come along, Ingenuity failed to check in.
Perseverance froze in its tracks. Scientists thought desperately about what might have happened
to the small helicopter. They theorised that if some kind of a fault had occurred on Ingenuity,
it was possible that it had gone into a safe, low-powered mode to persevere itself, thus
missing its communications window, or possibly desyncing its onboard clock from Perseverance’s.
As such, Perseverance waited a full day, listening all the while to see if Ingenuity would wake up
and start up communications again. And thankfully, it did. The little helicopter was all right,
reporting no major faults. However, its silence had been extremely worrying.
It turned out that the problem was the levels of dust in Mars’ air. Over time,
Ingenuity’s solar panels that kept its battery topped up had received less and less sunlight,
causing the batteries to dip dangerously low. Thanks to the freezing cold nights on Mars,
Ingenuity is only able to survive thanks to onboard heaters that keep its components warm.
Otherwise, freeze-thaw weathering would ultimately prove too much for it. Ingenuity was given several
days of lessened work, to give its batteries more time to charge up to operational levels. However,
this came at a cost – it would use its heaters less from here on. Instead of turning on its
heaters when temperatures reached -15°C, Ingenuity would only turn them on at -40°C.
And nights on Mars were about to get colder. Eventually, that cold will prove to be too much.
Although it was relieving that Ingenuity was all right, this was a grim reminder of one unavoidable
truth – time was not on this machine’s side. Eventually, dust would reduce its power absorption
rates to the point where it will not be able to keep itself heated. Its batteries will run down,
its components will break, and it will inevitably go silent. But that is why it’s more important
than ever to do what we can with the time we have left. Perseverance and Ingenuity
resynced their clocks, and headed off once more. Ahead of them lay the Delta. The most
likely place on Mars to locate signs of alien life. For now, their mission would continue.
It takes a lot of mathematical skills to get a rover to work, or a helicopter to
fly on Mars. You need to work out sunlight levels and power percentages. Air density,
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